There have been a number of occasions recently in which tanks holding explosive, toxic, or otherwise dangerous gases or liquids have been ruptured as the result of exposure to the heat of nearby fires. Stationary tanks containing pressurized gas and/or liquid have been exploded by heat radiated from burning buildings. Tanker trucks involved in accidents often survive the initial impact without sustaining ruptured tanks but if the truck catches fire as a result of the crash, the tank may then be ruptured due to overheating. Once the rupture occurs fire fighting and rescue operations become seriously complicated. The surrounding area must be evacuated and exposed bystanders may become seriously ill or lose their lives as the result of the ensuing secondary fires, explosions or release of toxic gases and fumes.
It is a well established fact that if a curtain of water can be provided around or on the surface of a tank or vessel, the tank and its contents can be protected thereby against fire damage. This protection occurs due to the fact that radiant heat from a nearby fire will be prevented from reaching the tank or its contents as it is absorbed by the intervening curtain of water. The heat so absorbed will heat the water, and if of sufficient intensity, will vaporize a portion of the water. The temperature of the tank and its contents are thus limited at worst to the boiling point of water.